Hydroxyapatite and cellulose nanocrystals loaded gelatin-chitosan based electrospun nanofibrous mats for rapid wound healing.

Electrospinning of a heterogeneous solution is difficult to continue because the required process parameters are different for multiple phases. In this study, nanofibrous mats were successfully prepared from a heterogeneous blend of solid cellulose nanocrystals (CNC) and hydroxyapatite nanoparticles (HAp) in a solution mixture of chitosan and gelatin using an electrospinning technique. HAp and CNC were used as filler materials in the nanofibrous mats. Gelatin and chitosan polymer chains in the mats were crosslinked using glutaraldehyde. The fiber diameter was noticed to decrease from around 86 to 43 nm with the increase of electrical conductivity of the spinning solution from 890 to 1166 µS cm-1 and after crosslinking a significant variation in fibers' diameter was noticed. The elemental analysis data showed that around 85% of the HAp used in the spinning solution was passed through the nozzle and the rest of the portion remained settled in the spinning syringe. In the XRD study, the crystallinity of chitosan, HAp and CNC was not observed in the non-crosslinked and crosslinked mats. The TGA analysis showed that the crosslinked mat has no weight retention at 500 °C which is due to its complete amorphous nature. The mats showed single-phase transition temperatures in DSC analysis which proves that no segregation of materials was present in the electrospun fibers. FTIR analysis of the mats showed a new peak at 1205 cm-1 which suggests the Michael addition type reactions to be happened between chitosan and gelatin. Cytotoxicity analysis of the mats on the vero-cell line showed around 95% of cell viability. The prepared mats were applied as wound dressings on a mice model experiment and 50% faster healing of wounds on the mice was noticed for the non-crosslinked mats than the control one.

Chitosan-Stabilized CuO Nanostructure-Functionalized UV-Crosslinked PVA/Chitosan Electrospun Membrane as Enhanced Wound Dressing.

Electrospun nanofibrous membranes are of great interest for tissue engineering, active material delivery, and wound dressing. These nanofibers possess unique three-dimensional (3D) interconnected porous structures that result in a higher surface-area-to-volume ratio and porosity. This study was carried out to prepare nanofibrous membranes by electrospinning a blend of PVA/chitosan polymeric solution functionalized with different ratios of copper oxide. Chitosan-stabilized CuO nanoparticles (CH-CuO NPs) were biosynthesized successfully utilizing chitosan as the capping and reducing agent. XRD analysis confirmed the monoclinic structure of CH-CuO NPs. In addition, the electrospun nanofibrous membranes were UV-crosslinked for a definite time. The membranes containing CH-CuO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectrophotometry, and dynamic light scattering (DLS). SEM results showed the nanosize of the fiber diameter in the range of 147-207 nm. The FTIR spectroscopy results indicated the successful incorporation of CH-CuO NPs into the PVA/chitosan nanofibrous membranes. DSC analysis proved the enhanced thermal stability of the nanofibrous membranes due to UV-crosslinking. Swelling and degradation tests were carried out to ensure membrane stability. Greater antimicrobial activity was observed in the nanoparticle-loaded membrane. An in vitro release study of Cu2+ ions from the membrane was carried out for 24 h. The cytotoxicity of CH-CuO NP-incorporated membranes was investigated to estimate the safe dose of nanoparticles. An in vivo test using the CH-CuO NP-loaded PVA/chitosan membrane was conducted on a mice model, in which wound healing occurred in approximately 12 days. These results confirmed that the biocompatible, nontoxic nanofibrous membranes are ideal for wound-dressing applications.

Silver nanoparticle reinforced polylactic acid and gelatin composite films for advanced wound dressing.

Multifunctional and biodegradable dressings with high mechanical strength and good antibacterial activity are crucial in fundamental health services. This study was initiated to prepare a novel curative wound dressing film consisting of natural biodegradable gelatin (G) and polylactic acid (PLA) with silver nanoparticles (AgNPs) where glutaraldehyde (GA) was used as compatibilizer. The prepared composite films addressed the poor thermal and biological stability of G and the limited fluid retention capacity of PLA. Silver nanoparticles were prepared by basic chemical reduction and reinforced on polymer films using simple solvent casting, which obviated common clinical infections and accelerated wound closure rate (p < .05). Fourier transform infrared (FTIR) studies confirmed composite formation through H-bonding and X-ray diffraction (XRD) revealed increased crystallinity due to incorporating AgNPs. Films with G, PLA & GA (50:50:5 by volume) introduced the best elasticity & strength with excellent fluid retention properties (p < .05). Scanning electron microscopy (SEM) images unfolded surface morphology and presence of agglomerated AgNPs on film surfaces. Prepared films exhibited significant antimicrobial efficacy against Staphylococcus aureus and Pseudomonas sp. and showed excellent cell viability (>97 %) in Vero cell line. Finally, an in vivo mouse model study showed 99.7 % contraction (p < .05) within 12 days, which was most effectual and 12 % faster than conventional gauge bandages. These results demonstrated the promising and cost-effective potential of the prepared film for wound healing.

The pectinolytic activity of Burkholderia cepacia and its application in the bioscouring of cotton knit fabric.

BACKGROUND: Enzymatic catalysis in different industrial applications is often preferred over chemical methods due to various advantages, such as higher specificity, greater efficiency, and less environmental footprint. Pectinases are a group of enzymes that catalyze the degradation of pectic compounds, the key components of plant middle lamella and the primary cell wall. Pectinases have found applications in multiple industrial processes, including cotton bioscouring, fruit juice extraction and its clarification, plant fiber degumming, paper making, plant biomass liquefaction, and saccharification, among others. The purpose of this study was to taxonomically characterize a bacterial species exhibiting pectinolytic activities and assess its pectinolytic activity qualitatively and quantitatively, as well as test its bioscouring potential. RESULTS: Here, we report that Burkholderia cepacia, a previously unknown species with pectinolytic activity, exerts such activity comparable to commercially used pectinase enzymes in the textile industry, but requires less temperature for activity. CONCLUSION: Quantitative evaluation of enzyme activity indicates the potential of the bacterial species for use in the bioscouring of cotton knit fabric.

Advanced CNC/PEG/PDMAA Semi-IPN Hydrogel for Drug Delivery Management in Wound Healing.

A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N'-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent system and then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N'-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and swelling properties of the hydrogel were investigated by different characterization techniques. The biocompatibility of the hydrogel was confirmed by cytotoxicity analysis, which showed >95% survival of the BHK-21, Vero cell line. The drug loaded hydrogel showed antimicrobial property by forming 25 and 23 mm zone of inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria, respectively, in antimicrobial analysis. At pH 5.5, 76% of the drug was released from the hydrogel within 72 h, as observed in an in vitro drug release profile. In an in vivo test, the healing efficiency of the drug loaded hydrogel was examined on a mice model with dorsal wounds. Complete healing of the wound without any scar formation was achieved in 12 days, which revealed excellent wound healing properties of the prepared drug loaded semi-IPN hydrogel. These results showed the relevance of such a system in the rapid healing of acute wounds.

Remarkable enhancement of thermal stability of epoxy resin through the incorporation of mesoporous silica micro-filler.

For the first time, we incorporated mesoporous micro-silica (5 µm, pore size = 50 nm) as a filler in epoxy resin aiming to enter polymer into the pore of the silica. As expected, the thermal stability of the composite increased remarkably, followed by noteworthy thermal degradation kinetics when compared to the controlled cured epoxy resin. Composites were prepared by the direct dispersion of modified nano-silica, modified mesoporous micro-silica, unmodified mesoporous micro-silica, non-porous micro-silica, and irregular micro-silica of various pore sizes as fillers in diglycidyl ether of bisphenol-A epoxy resin via ultra-sonication and shear mixing, followed by oven-curing with 4,4-diaminodiphenyl sulfone. DSC and TGA analyses demonstrated a higher glass transition temperature (increased by 3.65-5.75 °C) and very high activation energy for thermal degradation (average increase = 46.2%) was obtained for the same unmodified silica composite compared to pure epoxy, respectively.

Novel alginate-di-aldehyde cross-linked gelatin/nano-hydroxyapatite bioscaffolds for soft tissue regeneration.

The present study describes the fabrication of a novel alginate-di-aldehyde (ADA) cross-linked gelatin (GEL)/nano-hydroxyapatite (nHAp) bioscaffold by lyophilization process. The physico-chemical properties of the scaffolds were evaluated in order to assess its suitability for tissue engineering application. ADA was prepared from periodate oxidation of alginate which facilitate the crosslinking between free amino group of gelatin and available aldehyde group of ADA through Schiff's base formation. nHAp was synthesized from waste egg-shells by wet chemical method. The synthesized HAp was found crystalline and nanosize (~45 nm) by XRD and TEM analysis respectively. Ca to P ratio of nHAp is 1.51 as observed by EDX confirmed the suitability of the scaffold for biomedical application. The crosslinked ADA increases thermal stability of scaffolds. Water uptake and degradation ability significantly reduced with the increase of nHAp in the scaffold due to the higher stiffness contributed by nHAp. SEM analysis revealed that the pore size and porosity of the scaffolds declines with the proliferation of nHAp in the scaffolds. XRD analysis of the scaffolds shows the increase of crystallinity in the composites due to incorporation of nHAp and ADA. Cytotoxicity of the all scaffolds were examined by normal kidney epithelial cells (Vero cells) and the results confirmed the non-toxicity of the scaffolds, which proved it is extremely cytocompatible. These tunable physical properties and enhance biocompatibility of prepared scaffold offer advance application in soft tissue regeneration and could be a promising candidate for biomedical application.

Core-shell drug carrier from folate conjugated chitosan obtained from prawn shell for targeted doxorubicin delivery.

A multifunctional drug carrier with dual targeting (magnetic and folate-receptor) and pH sensitive core-shell hybrid nanomaterial has been developed to carry an anticancer drug doxorubicin.Superparamagnetic iron oxide nanoparticles (IONPs) were used as core of the carrier and cross-linked folate conjugated chitosan (FA-CS) was acted as shell in which doxorubicin was physically entrapped. Transmission electron microscopy (TEM) analysis confirmed the average particle size of IONPs and FA-CS coated IONPs 8.2 and 15.4 nm respectively. Magnetic measurement indicated that both the IONPs and FA-CS coated IONPs were superparamagnetic at room temperature with a magnetization value 57.72 and 37.44 emu/g respectively. At pH 5.8 (malignant tissue) showed a burst release of 30.05% of the doxorubicin in the first 4 h followed by a sustained release of 88.26% of drug over 72 h. From these results it is expected that doxorubicin loaded nanoparticles can be a promising drug carrier for the treatment of solid tumors with the ability to reduce toxic side effects of drugs by selective targeting and sustained release.

Preparation of Chitin-PLA laminated composite for implantable application.

The present study explores the possibilities of using locally available inexpensive waste prawn shell derived chitin reinforced and bioabsorbable polylactic acid (PLA) laminated composites to develop new materials with excellent mechanical and thermal properties for implantable application such as in bone or dental implant. Chitin at different concentration (1-20% of PLA) reinforced PLA films (CTP) were fabricated by solvent casting process and laminated chitin-PLA composites (LCTP) were prepared by laminating PLA film (obtained by hot press method) with CTP also by hot press method at 160 °C. The effect of variation of chitin concentration on the resulting laminated composite's behavior was investigated. The detailed physico-mechanical, surface morphology and thermal were assessed with different characterization technique such as FT-IR, XRD, SEM and TGA. The FTIR spectra showed the characteristic peaks for chitin and PLA in the composites. SEM images showed an excellent dispersion of chitin in the films and composites. Thermogravimetric analysis (TGA) showed that the complete degradation of chitin, PLA film, 5% chitin reinforced PLA film (CTP2) and LCTP are 98%, 95%, 87% and 98% respectively at temperature of 500 °C. The tensile strength of the LCTP was found 25.09 MPa which is significantly higher than pure PLA film (18.55 MPa) and CTP2 film (8.83 MPa). After lamination of pure PLA and CTP2 film, the composite (LCTP) yielded 0.265-1.061% water absorption from 30 min to 24 h immerse in water that is much lower than PLA and CTP. The increased mechanical properties of the laminated films with the increase of chitin content indicated good dispersion of chitin into PLA and strong interfacial actions between the polymer and chitin. The improvement of mechanical properties and the results of antimicrobial and cytotoxicity of the composites also evaluated and revealed the composite would be a suitable candidate for implant application in biomedical sector.

Characterization of crystalline cellulose of jute reinforced poly (vinyl alcohol) (PVA) biocomposite film for potential biomedical applications.

Cellulose crystals (CC) were chemically derived from jute by alkali treatment, bleaching and subsequent hydrolysis with 40 % sulfuric acid. Infrared spectroscopy (FT-IR) suggested sufficient removal of lignin and hemicellulose from the raw jute and scanning electron microscopy (SEM), and X-ray diffraction (XRD) studies demonstrated the preparation of microcrystalline cellulose. CC reinforced polyvinyl alcohol (PVA) composite was prepared by solution casting method under laminar flow. In order to maintain uniform dispersion of 3-15 % (w/w) of the CC in the composite N, N dimethylformamide (DMF) was used as a dispersant. FT-IR, XRD, SEM, thermogravimetric analysis (TG, DTG and DTA) and thermomechanical analyses (TMA) were used to characterize the CC and the composites. The study of tensile properties showed that tensile strength (TS) and modulus (TM) increase with increasing CC content up to 9 % and then decrease with the addition of a high content of CC (above 9 %) because of the aggregation of CCs in the composite. The highest TS (43.9 MPa) and TM (2,190 MPa) have been shown to be the composite prepared with 9 % CC and the lowest to be from pure PVA film 17.1 and 1470 MPa. In addition, the composites have showed no cytotoxicity that can also prohibit microbial growth and; hence, it can be a potential material for biomedical applications such as wound healing accelerators.

Investigation of crystallinity, molecular weight change, and mechanical properties of PLA/PBG bioresorbable composites as bone fracture fixation plates.

In this study, bioresorbable phosphate-based glass (PBG) fibers were used to reinforce poly(lactic acid) (PLA). PLA/PBG random mat (RM) and unidirectional (UD) composites were prepared via laminate stacking and compression molding with fiber volume fractions between 14% and 18%, respectively. The percentage of water uptake and mass change for UD composites were higher than the RM composites and unreinforced PLA. The crystallinity of the unreinforced PLA and composites increased during the first few weeks and then a plateau was seen. XRD analysis detected a crystalline peak at 16.6° in the unreinforced PLA sample after 42 days of immersion in phosphate buffer solution (PBS) at 37°C. The initial flexural strength of RM and UD composites was ∼106 and ∼115 MPa, whilst the modulus was ∼6.7 and ∼9 GPa, respectively. After 95 days immersion in PBS at 37°C, the strength decreased to 48 and 52 MPa, respectively as a result of fiber-matrix interface degradation. There was no significant change in flexural modulus for the UD composites, whilst the RM composites saw a decrease of ∼45%. The molecular weight of PLA alone, RM, and UD composites decreased linearly with time during degradation due to chain scission of the matrix. Short fiber pull-out was seen from SEM micrographs for both RM and UD composites.